This is not an isolated case of ongoing corporate cheating. Last September, the U.S. Environmental Protection Agency revealed that Volkswagen had been cheating on emissions tests for years. Similar examples of unethical behavior abound in many other industries, from banking to insurance to health care.

Why do so many organizational leaders and employees (even those who care about being honest people) consistently engage in morally questionable behaviors over time? We recently conducted research aimed at answering this question, found that faulty human memory helps to explain repeated dishonesty.

When people fail to live up to their own moral standards, this knowledge is unpleasant and threatens their self-image as honest and good. Consequently, they engage in various strategies to reduce their distress, including forgetting these memories. Such memory biases and distortions are not accidental; rather, they are motivated to support our self-concept and identity.

In our research, we found that people are more likely to forget the details of their own unethical acts as compared to other incidents — including neutral, negative, and positive events, and the unethical actions of others. We call this tendency unethical amnesia, or obfuscation of one’s unethical acts over time. Unethical amnesia is an adaptive mechanism for coping with the psychological distress and discomfort of behaving unethically.

We found evidence of unethical amnesia across nine experimental studies involving diverse sample populations, ranging from undergraduate students to online panels of adults. In our studies, we compared individuals’ memories of different types of events to examine the quality (including vividness and level of detail) of their memories of their unethical acts as compared with other acts.

For instance, in one of our studies, we relied on individuals’ past experiences and found that people who recalled and wrote about behaving unethically were less likely to remember the details of their actions a few days later as compared to people who engaged in ethical behavior and people who recalled and wrote about positive or negative (but not unethical) actions.

In another study, we asked participants to read a detailed story of an unethical act. Some read a third-person story about another person; others read a first-person story asking them to imagine being in the shoes of the person described in the story. Here again, people tended to forget their “own” unethical acts but remembered those of other people.

We also conducted a study in which participants had the opportunity to cheat on a die-throwing game to earn money by misreporting their performance. We then measured their memory a few days later. What we found is that participants who cheated had less clear, less vivid, and less detailed memories of their actions as compared to those who behaved honestly.

We also examined the consequences of unethical amnesia. In two of our studies, for instance, a few days after giving participants an opportunity to cheat and misreport their performance for extra money, we gave them another chance to do so. We found that initial cheating inspired unethical amnesia, which drove further unethical behavior on the subsequent task.

Overall, our findings demonstrate a consistent reduction in the clarity and vividness of people’s memory of their past unethical actions, which also explains why they repeatedly behave dishonestly over time. Unethical actions, our research shows, tend to be forgotten; when remembered, memories of unethical behavior are less clear than memories of other types of positive and negative behaviors.

Understanding the psychology that drives decisions can help us make sense of corporate cheating scandals and, hopefully, behave more ethically, and promote more ethical behavior in our own organizations.